title: Mouse IgA heavy chain gene sequence: implications for evolution of immunoglobulin hinge axons.
abstract: The complete nucleotide sequence of the gene and mRNA coding for the constant (C) region of the secreted form of the BALB/c mouse IgA immunoglobulin alpha heavy (H) chain has been determined. As in other immunoglobulins, the three C region domains of the alpha protein, C alpha 1, C alpha 2, and C alpha 3 are coded in separate exons. However, the hinge region of C alpha is not coded on a separate exon as it is in other hinge-containing immunoglobulins. Instead, the alpha hinge is coded as a 5' extension of the C alpha 2 exon, and we suggest that it may have evolved by duplication leading to incorporation of an acceptor RNA splice site into the coding portion of the C alpha 2 exon. Extensions of this concept could provide an explanation for duplications in the human alpha 1 chain.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D003062:Codon; D005796:Genes; D007127:Immunoglobulin Constant Regions / Q000235:genetics*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007137:Immunoglobulin alpha-Chains / Q000235:genetics*; D007136:Immunoglobulins / Q000235:genetics*; D051379:Mice; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D003062:Codon; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007137:Immunoglobulin alpha-Chains; D007136:Immunoglobulins; D012333:RNA, Messenger